ALUN ANDERSON is a senior consultant at New Scientist.
A common image in popular accounts of the “Mind” is a brain in a bell jar with a pair of eyeballs staring out at the world. The message is that a disembodied lump of neural tissue can be everything that is you: your thoughts, feelings, and emotions.
But perhaps that is all wrong. Perhaps thought and feeling are only possible because the brain interacts with its body and listens to the things it tells it. And perhaps much of how the brain understands the world is only possible becuase of the brain’s experience of controlling a body.
These are dangerous ideas as they lead us to rethink what the brain really does and to question whether the traditional divide between brain and body makes sense. If we abandon that traditional divide, then doctors will have to accept that states of mind and states of health are tied together in a way that conventional medical science has never felt comfortable with. We’ll also have to think again about feelings like falling in love, which are located just as much in the body as in the mind. And we’ll need a new approach to develop machines with humanlike social intelligence.
We’ve probably fallen for the myth that the brain can be considered apart from the body because of the academic tendency to worship abstract thought. Philosophers like to sit still and think. But much more of the brain’s power is used to plan and control movement than for cogitation. Sportswriters get it right when they describe stars of football or baseball as “geniuses”! Their skills do require impressive brainpower as well as a superb body, which means they have more to strive for than Einstein.
Interactions between mind and body come out strongly in the surprising links between status and health. The epidemiologist Michael Marmot’s celebrated studies show that the lower you are in the pecking order, the worse your health is likely to be. You can explain away only a small part of the trend by poorer access to health care or poorer food or living conditions. For Marmot, the answer lies in “the impact over how much control you have over life circumstances.” The important message is that state of mind—perceived status—translates into state of body.
The effect of placebos on health delivers a similar message. Trust and belief are often seen as negative in science, and the placebo effect is dismissed as a kind of fraud because it relies on the belief of the patient. But the real wonder is that faith can work. Placebos can stimulate the release of pain-relieving endorphins and affect neuronal firing rates in people with Parkinson’s disease.
Body and mind interact too in the most intimate feelings of love and bonding. Those interactions have been best explored in voles where two hormones, oxytocin and vasopressin, are critical. The hormones are released as a result of “the extended tactile pleasures of mating,” as researchers put it, and hit pleasure centers in the brain that essentially addict sexual partners to each other.
Humans are surely more cerebral. But brain scans of people in love show heightened activity where there are lots of oxytocin and vasopressin receptors. Oxytocin levels rise during orgasm and sexual arousal, as they do from touching and massage. There are defects in oxytocin receptors associated with autism. And the hormone boosts the feeling that you can trust others, which is a key part of intimate relations. In a recent laboratory “investment game,” many investors would trust all their money to a stranger after a puff of an oxytocin spray.
These few stories show the importance of the interplay of minds and hormonal signals, of brains and bodies. This idea has been taken to a profound level in the studies of the neuroscientist Antonio Damasio, who finds that “gut feelings” are essential to making decisions. “We don’t separate emotion from cognition like layers in a cake,” says Damasio. “Emotion is in the loop of reason all the time.”
Indeed, the way in which reasoning is tied to body actions may be counterintuitive. Giacomo Rizzolatti of the University of Parma discovered mirror neurons in a part of the monkey brain responsible for planning movement. These nerve cells fire both when a monkey performs an action (like picking up a peanut) and when the monkey sees someone else do the same thing. Before long, similar systems were found in human brains, too.
The surprising conclusion may be that when we see someone do something, the same parts of our brain are activated as if we were doing it ourselves. We may know what other people intend and feel by simulating what they are doing within the same motor areas of our own brains. As Rizzolatti puts it, “The fundamental mechanism that allows us a direct grasp of the mind of others is not conceptual reasoning but direct simulation of the observed events through the mirror mechanism.” Direct grasp of others’ minds is a special ability that paves the way for our unique powers of imitation, which in turn have allowed culture to develop.
If bodies and their interaction with brain and planning for action in the world are so central to human kinds of mind, where does that leave the chances of creating an intelligent disembodied mind inside a computer? Perhaps the Turing test will be harder than we think. We may build computers that understand language but cannot say anything meaningful, at least until we can give them “extended tactile experiences.” To put it another way, computers may not be able to make sense until they can have sex.